1. Field of the Invention
The present invention relates to a method and an apparatus for resetting a peripheral device connected to a computer system, such as an optical disk drive, and more particularly to a method and an apparatus, in which a reset signal output from a host computer system is reliably discriminated from the other noise signals.
2. Description of the Related Art
A peripheral device, for example, an optical disk drive serving an external memory device, is connected to a host computer system by a Small Computer System Interface, herein after denotes SCSI.
In general, the optical disk drive includes an interface section that is connected to the host computer system via the SCSI. The interface section receives various signals from the host computer system. It outputs control signals for controlling movable mechanisms in the disk drive and for updating or maintaining the contents of a temporary storage section based on signals supplied from the host computer system. The optical disk drive further includes a driving mechanism control section for controlling the movable mechanisms driven in order to record/read data in/from an optical disk member in accordance with the control signals output from the interface section.
This type of memory device, i.e., the optical disk drive, has a reset function for clearing data which is being input thereto or data which is being to be stored in the optical disk based on a cleaning operation of mechanical controller.
When a reset signal is input to the optical disk drive from the host system via the SCSI, the reset function is enabled and to interrupt the other processes which have been previously input.
According to SCSI protocol, the reset signal becomes "true" (when the reset signal is presented), when the optical disk drive detects that a reset signal is input. The reset function is enabled in response to such detection. Therefore, the optical disk drive may be unexpectedly reset by noise which may occur when signals in a bus line under the SCSI are switched. The consequence is that data may be stored lost.